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Claude Opus 4.8 vs Gemini 3.8 Flash

Claude Opus 4.8 leads Gemini 3.8 Flash on coding, 65.0 to 61.6 on the Vibe Coding Index, and Gemini 3.8 Flash costs 6.7x less per output token ($3.75 vs $25.00 per million). Updated October 21, 2026; 114 benchmarks have a result for both.

Replace Claude Opus 4.8 Replace Gemini 3.8 Flash
Claude Opus 4.8Anthropic
Coding
65.0
Overall
69.8
Output $/M
$25.00
36
Gemini 3.8 FlashGoogle
Coding
61.6
Overall
69.0
Output $/M
$3.75
76
vs boards won of 114 shared, 2 tied

Claude Opus 4.8 or Gemini 3.8 Flash: which to pick

Pick Claude Opus 4.8 for coding: it scores 65.0 on the Vibe Coding Index against 61.6 for Gemini 3.8 Flash.

Pick Gemini 3.8 Flash for output tokens 6.7x cheaper ($3.75 vs $25.00 per million) and a larger context window (1.05M against 1M tokens).

Model AClaude Opus 4.8Anthropic65.0/1006 independent benchmarks$2.17 per solved taskModel BGemini 3.8 FlashGoogle61.6/1006 independent benchmarks$2.74 per solved task
Shared results
114
Claude Opus 4.8 only
16
Gemini 3.8 Flash only
14
Like-for-like categories
8 of 9

Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.

Which one for your work

Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.

At a glance

Coding index
Claude Opus 4.8 65.0 from 6 benchmarks, Gemini 3.8 Flash 61.6 from 6 benchmarks.
Widest category
Math, 13.1 points apart on average over 6 shared benchmarks.
Widest single gap
FrontierMath, tier 4: Claude Opus 4.8 56.1% against Gemini 3.8 Flash 22.0%, 34.1 points apart on a 0 to 100 scale.
Output price
Claude Opus 4.8 $25.00 against Gemini 3.8 Flash $3.75 per million output tokens, 6.7x apart.
Context window
Claude Opus 4.8 takes 1M tokens, Gemini 3.8 Flash 1.05M.

Benchmark by benchmark

First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.

Boards won, where both have a result
CategoryClaude Opus 4.8BarsGemini 3.8 FlashTies
Coding6112 ties
Intelligence20
Agentic work119
Reasoning114
Math33
Knowledge38
Web design27
General824
All shared boards36762 ties
CodingLike-for-likeSix of these boards feed the Vibe Coding Index611
Coding benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
LiveBench coding77.3%82.2%Gemini 3.8 Flash
LMArena WebDev15561585Gemini 3.8 Flash
AA Coding Index74.376.3Gemini 3.8 Flash
LiveCodeBench (Vals AI)87.8%89.5%Gemini 3.8 Flash
SWE-bench Verified (Vals AI)88.6%80.0%Claude Opus 4.8
Terminal-Bench 4 (Vals AI)23.2%19.7%Claude Opus 4.8
Vibe Code Bench (Vals AI)82.7%78.7%Claude Opus 4.8
Code migration (Vals AI)47.3%36.5%Claude Opus 4.8
ProgramBench (Vals AI)1.0%1.0%Tie
IOI (Vals AI)Not measured56.9%Only Gemini 3.8 Flash measured
Terminal-Bench 2.1 (Vals AI)71.9%81.3%Gemini 3.8 Flash
SWE-bench Multimodal (Vals AI)Not measured40.8%Only Gemini 3.8 Flash measured
Vibe Code Bench 1-100 (Vals AI)Not measured18.8%Only Gemini 3.8 Flash measured
SkillsBench (Vals AI)59.2%58.0%Claude Opus 4.8
CyberBench (Vals AI)Not measured43.8%Only Gemini 3.8 Flash measured
SciCode54.4%56.6%Gemini 3.8 Flash
Terminal-Bench Hard (Artificial Analysis run)58.3%Not measuredOnly Claude Opus 4.8 measured
FrontierCode46.5%41.2%Claude Opus 4.8
FrontierSWENot measured19.6%Only Gemini 3.8 Flash measured
GSO-Bench47.1%Not measuredOnly Claude Opus 4.8 measured
WeirdML82.9%84.8%Gemini 3.8 Flash
ALE-BenchNot measured1269.7Only Gemini 3.8 Flash measured
LMArena Text: coding14901508Gemini 3.8 Flash
LMArena Text: software and IT14881507Gemini 3.8 Flash
LMArena WebDev: React15571577Gemini 3.8 Flash
LMArena WebDev: HTML15431616Gemini 3.8 Flash
LMArena WebDev: from an imageNot measured1593Only Gemini 3.8 Flash measured
SciCode12.3%12.3%Tie
Neither model has a result on the other 11 boards here
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index20
Intelligence benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
AA Intelligence Index41.840.9Claude Opus 4.8
Epoch Capabilities Index159.0157.4Claude Opus 4.8
Agentic workLike-for-likePublic boards, shown as published, kept out of the index119
Agentic work benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
AA Agentic Index41.940.2Claude Opus 4.8
Design Arena: agents building web apps12331238Gemini 3.8 Flash
Design Arena: agents building full-stack apps12491244Claude Opus 4.8
Design Arena: agents building mobile apps12221236Gemini 3.8 Flash
Design Arena: agents building Android apps12321074Claude Opus 4.8
Design Arena: agents building Godot games12311273Gemini 3.8 Flash
Design Arena: agents building games1238Not measuredOnly Claude Opus 4.8 measured
Design Arena: HTML slides1221Not measuredOnly Claude Opus 4.8 measured
Design Arena: PowerPoint slides12271177Claude Opus 4.8
Design Arena: spreadsheets12701056Claude Opus 4.8
LiveBench research81.8%79.1%Claude Opus 4.8
LiveBench browser96.0%64.0%Claude Opus 4.8
LiveBench long agentic48.3%30.1%Claude Opus 4.8
SREBench (Vals AI)Not measured11.1%Only Gemini 3.8 Flash measured
Finance Agent (Vals AI)53.9%61.4%Gemini 3.8 Flash
Tax Agent Bench (Vals AI)30.0%32.1%Gemini 3.8 Flash
Legal Research Bench (Vals AI)43.8%38.9%Claude Opus 4.8
Harvey's Legal Agent Benchmark (Vals AI)Not measured12.1%Only Gemini 3.8 Flash measured
Excel Modeling Benchmark (Vals AI)69.4%72.2%Gemini 3.8 Flash
BioMysteryBench (Vals AI)Not measured62.2%Only Gemini 3.8 Flash measured
Terminal-Bench-Science (Vals AI)4.3%8.6%Gemini 3.8 Flash
Vals Science IndexNot measured35.8%Only Gemini 3.8 Flash measured
Time Horizon Index (Vals AI)11.8%18.8%Gemini 3.8 Flash
CUA-bench (Vals AI)Not measured4.2%Only Gemini 3.8 Flash measured
τ²-Bench Telecom94.4%Not measuredOnly Claude Opus 4.8 measured
APEX-Agents48.9%64.3%Gemini 3.8 Flash
Remote Labor Index8.3%5.8%Claude Opus 4.8
OSWorld 2.020.6%Not measuredOnly Claude Opus 4.8 measured
DeepResearch Bench50.2%Not measuredOnly Claude Opus 4.8 measured
PostTrainBench33.8%Not measuredOnly Claude Opus 4.8 measured
Vending-Bench 2$5,787$5,094Claude Opus 4.8
LMArena Search1204Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 9 boards here
ReasoningLike-for-likePublic boards, shown as published, kept out of the index114
Reasoning benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
GPQA Diamond92.4%94.4%Gemini 3.8 Flash
LiveBench reasoning89.2%89.3%Gemini 3.8 Flash
MysteryMechanism (Vals AI)Not measured36.5%Only Gemini 3.8 Flash measured
MMMU Pro (Vals AI)86.6%89.1%Gemini 3.8 Flash
GPQA Diamond (Artificial Analysis run)92.0%95.3%Gemini 3.8 Flash
Humanity's Last Exam (Artificial Analysis run)48.7%47.8%Claude Opus 4.8
GPQA Diamond (Epoch AI run)91.0%95.4%Gemini 3.8 Flash
ARC-AGI92.5%98.5%Gemini 3.8 Flash
ARC-AGI-272.1%89.2%Gemini 3.8 Flash
SimpleBench64.8%Not measuredOnly Claude Opus 4.8 measured
Chess puzzles52.0%58.0%Gemini 3.8 Flash
Mystery game puzzles36.0%47.0%Gemini 3.8 Flash
EBR-bench28.6%Not measuredOnly Claude Opus 4.8 measured
LMArena Text: hard prompts14821509Gemini 3.8 Flash
LMArena Text: expert15031526Gemini 3.8 Flash
LMArena Text: hard prompts in English14871504Gemini 3.8 Flash
LMArena Vision: diagrams13151345Gemini 3.8 Flash
LMArena Vision: homework13371351Gemini 3.8 Flash
Kagi LLM Benchmark88.8%Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 3 boards here
MathLike-for-likePublic boards, shown as published, kept out of the index33
Math benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
OTIS Mock AIME98.3%98.9%Gemini 3.8 Flash
FrontierMath, tiers 1 to 380.0%68.4%Claude Opus 4.8
FrontierMath, tier 456.1%22.0%Claude Opus 4.8
ProofBench69.0%48.0%Claude Opus 4.8
LMArena Text: math14861532Gemini 3.8 Flash
LMArena Text: mathematical work14971519Gemini 3.8 Flash
Neither model has a result on the other 7 boards here
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index38
Knowledge benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
MMLU Pro89.6%90.2%Gemini 3.8 Flash
LegalBench (Vals AI)83.6%87.0%Gemini 3.8 Flash
CorpFin (Vals AI)66.7%Not measuredOnly Claude Opus 4.8 measured
TaxEval (Vals AI)75.6%74.5%Claude Opus 4.8
MortgageTax (Vals AI)69.9%65.3%Claude Opus 4.8
MedCode (Vals AI)53.2%48.1%Claude Opus 4.8
SimpleQA Verified53.0%69.7%Gemini 3.8 Flash
LMArena Text: science14771523Gemini 3.8 Flash
LMArena Text: medicine and healthcare14641508Gemini 3.8 Flash
LMArena Text: legal and government14771497Gemini 3.8 Flash
LMArena Text: business and finance14581479Gemini 3.8 Flash
FACTS Benchmark Suite53.5%69.4%Gemini 3.8 Flash
Neither model has a result on the other 6 boards here
Web designLike-for-likePublic boards, shown as published, kept out of the index27
Web design benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
Design Arena: websites12591300Gemini 3.8 Flash
Design Arena: UI components12571319Gemini 3.8 Flash
Design Arena: game dev12641305Gemini 3.8 Flash
Design Arena: data viz12401269Gemini 3.8 Flash
Design Arena: 3D12231295Gemini 3.8 Flash
Design Arena: all code categories12551304Gemini 3.8 Flash
Design Arena: SVG11941295Gemini 3.8 Flash
Design Arena: ASCII art12771265Claude Opus 4.8
LiveBench design78.8%72.7%Claude Opus 4.8
GeneralLike-for-likePublic boards, shown as published, kept out of the index824
General benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
Vals IndexNot measured56.0%Only Gemini 3.8 Flash measured
LiveBench data analysis66.0%54.0%Claude Opus 4.8
Public Benefits Bench (Vals AI)68.1%65.3%Claude Opus 4.8
SAGE (Vals AI)54.8%35.1%Claude Opus 4.8
MedScribe (Vals AI)85.8%84.5%Claude Opus 4.8
Vals Multimodal Index70.9%Not measuredOnly Claude Opus 4.8 measured
IFBench62.2%Not measuredOnly Claude Opus 4.8 measured
Long context reasoning (AA-LCR)77.7%84.0%Gemini 3.8 Flash
DTBench94.9%95.7%Gemini 3.8 Flash
LMCA57.5%52.9%Claude Opus 4.8
Surface Evolver Bench87.5%76.9%Claude Opus 4.8
Furniture assembly42.5%31.7%Claude Opus 4.8
LMArena Text14611499Gemini 3.8 Flash
LMArena Text: instruction following14761492Gemini 3.8 Flash
LMArena Text: creative writing14541488Gemini 3.8 Flash
LMArena Vision12941315Gemini 3.8 Flash
LMArena Text: English14681498Gemini 3.8 Flash
LMArena Text: non-English14501491Gemini 3.8 Flash
LMArena Text: Chinese15061553Gemini 3.8 Flash
LMArena Text: German14721501Gemini 3.8 Flash
LMArena Text: Japanese14421507Gemini 3.8 Flash
LMArena Text: Korean14311464Gemini 3.8 Flash
LMArena Text: French14811496Gemini 3.8 Flash
LMArena Text: Spanish14651487Gemini 3.8 Flash
LMArena Text: Russian14741514Gemini 3.8 Flash
LMArena Text: Polish14591497Gemini 3.8 Flash
LMArena Text: multi-turn14761503Gemini 3.8 Flash
LMArena Text: longer queries14831507Gemini 3.8 Flash
LMArena Text: writing and language14611494Gemini 3.8 Flash
LMArena Text: entertainment and media14401480Gemini 3.8 Flash
LMArena Vision: English12931318Gemini 3.8 Flash
LMArena Vision: Chinese13461416Gemini 3.8 Flash
LMArena Vision: reading text13031333Gemini 3.8 Flash
LMArena Vision: humor12821321Gemini 3.8 Flash
LMArena Vision: creative writing13011299Claude Opus 4.8
LMArena Document1475Not measuredOnly Claude Opus 4.8 measured
Neither model has a result on the other 10 boards here
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
Image generation benchmarks for Claude Opus 4.8 and Gemini 3.8 Flash
BenchmarkClaude Opus 4.8Gemini 3.8 FlashLeader
Neither model has a result on 5 boards here

What each workload costs

Three fixed token mixes at each model's listed price, so per-token rates become a bill.

Chat turn

1K input + 500 output tokens

Claude Opus 4.8$0.018Fits in one request
Gemini 3.8 Flash$0.0026Fits in one request

Gemini 3.8 Flash costs less

Repository review

50K input + 3K output tokens

Claude Opus 4.8$0.325Fits in one request
Gemini 3.8 Flash$0.049Fits in one request

Gemini 3.8 Flash costs less

Agent loop

200K input + 10K output tokens

Claude Opus 4.8$1.25Fits in one request
Gemini 3.8 Flash$0.188Fits in one request

Gemini 3.8 Flash costs less

Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.

Specification differences

The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.

Specifications of Claude Opus 4.8 and Gemini 3.8 Flash
SpecificationAnthropic Claude Opus 4.8Google Gemini 3.8 Flash
MakerAnthropicGoogle
WeightsNo public weights listedNo public weights listed
ReleasedMay 27, 2026September 2, 2026
Context window1M1.05M
Input $/Mtok$5.00$0.75
Output $/Mtok$25.00$3.75
Coding index65.061.6
Independent measurements behind it66
Cost per solved task$2.17$2.74
SourceOpenRouter listingOpenRouter listing

Questions

Is Claude Opus 4.8 better than Gemini 3.8 Flash for coding?

Pick Claude Opus 4.8 for coding: it scores 65.0 on the Vibe Coding Index against 61.6 for Gemini 3.8 Flash. Pick Gemini 3.8 Flash for output tokens 6.7x cheaper ($3.75 vs $25.00 per million) and a larger context window (1.05M against 1M tokens).

Which is cheaper, Claude Opus 4.8 or Gemini 3.8 Flash?

Claude Opus 4.8 costs $5.00 per million input tokens and $25.00 per million output tokens; Gemini 3.8 Flash costs $0.75 and $3.75. Per solved SWE-bench Verified task, Claude Opus 4.8 costs $2.17 and Gemini 3.8 Flash $2.74.

Which has the bigger context window, Claude Opus 4.8 or Gemini 3.8 Flash?

Gemini 3.8 Flash, with 1.05M tokens against 1M.

How many benchmarks is the Claude Opus 4.8 vs Gemini 3.8 Flash comparison based on?

114 benchmarks have a result for both models as of October 21, 2026. Claude Opus 4.8's coding index rests on 6 independent benchmarks and Gemini 3.8 Flash's on 6. Where only one model has a result, the page says so instead of naming a winner.

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